A major concern for users of collecting devices, such as ostomy devices for collecting fecal output from the stoma, is the occurrence of leakage during wear. Herein, a leakage or leak is understood as being output from a stoma, or other body opening, that works its way in between the skin and the adhesive interface of the ostomy device, all the way from the stoma to the outer periphery of the adhesive wafer. Apart from being unhealthy to the skin that gets in contact with the stoma output, the leak often results in discomfort and potential embarrassing situations for the user.
One way of reducing the risk of leakage is by dividing the adhesive wafer, which attaches the ostomy device to the skin of the user, in a radial inner and a radial outer adhesive layer. The two layers being separated by an opening.
In this way, when a crack starts to propagate between the inner adhesive layer and the skin, the crack will stop when it reaches the opening. A new crack will have to be initiated in the radial outer adhesive layer before leakage can occur. Thus, the opening works as a barrier reducing the risk of leakage occurring, or at least increasing the time for a leakage to occur.
Such a configuration is, for example, known from WO2007/121744.
However, there is still a tendency for a leakage to occur relatively quickly after the inner adhesive layer detaches.
Often, when a leakage occurs, what happens is that a crack is initiated at a weak spot. This crack propagates from the center of the adhesive in a radial direction through the adhesive/skin interface driven by forces between the skin substrate and the adhesive plate. Such forces can originate from body movements and/or from pressure build-up in the collecting bag propagating through the bag wall and cannot be avoided. Throughout the crack propagation, the mode in which the adhesive slips the skin substrate is by way of peeling. Even in two zone adhesives where the adhesive wafer consists of a radially inner and outer adhesive, the forces acting on the adhesive will stay in a crack propagating peel mode, resulting in poor resistance to leakage after initialization of the crack.
When the leak has propagated all the way to the void between the inner and outer adhesive layers, body waste output can flow freely through the leakage. This means that if a pressure is created in the collecting bag this pressure will be transmitted through the leak and into the void. Here, it will generate a peeling force on the radial outer adhesive layer that will propagate quickly through the adhesive/skin interface and all the way to the user's clothes.